Engineering <scp>3D</scp> diffusion channels in a <scp>COF</scp> through <scp>pH</scp> ‐dependent slipping for enhanced <scp> CO ₂ </scp> capture

Abstract Covalent organic frameworks (COFs) are considered promising adsorbents for CO 2 capture due to their tailorable molecular structures and high surface areas. However, their practical application is often constrained by the simple and uniform pore architectures of conventional COFs, which severely limit gas diffusion kinetics and the accessibility of binding sites. To address this issue, we report a facile acid‐treatment strategy which induces interlayer slipping in a two‐dimensional NO 2 ‐TpBD‐COF, transforming it into a quasi‐three‐dimensional network with interconnected channels. The optimized material (NO 2 ‐TpBD‐COF‐2‐5, treated at pH = 2 for 5 days) exhibits an 87% increase in BET surface area from 582 to 1092 m 2 ·g −1 and a 29% enhancement in CO 2 uptake capacity from 37.74 to 48.73 cm 3 ·g −1 . Molecular simulations (GCMC and MD) reveal that the performance improvement stems from the newly formed 3D cross‐linked channels, which provide highly efficient pathways for CO 2 diffusion and significantly improve site accessibility.